First Report of Muskmelon Fruit Rot Caused by Fusarium sulawesiense in China.

Muskmelon (Cucumis melo L.) is a widely cultivated and economically important fruit crop worldwide. In June 2022, fruit rot symptoms were observed on ripening muskmelons (cv. Boyang) in Shouguang City (36.81°N 118.90°E) of China. To determine the causal agent, we surveyed 200 muskmelon plants in about 1000 m2 of planting area and collected diseased muskmelons. Approximately 20% of muskmelon fruits had symptoms, and yield loss averaged 20%. Water-soaked lesions were observed on the surface and the fruit rotted from inside. Lesions were covered with white mycelium. Rotted fruit were surface-disinfested with 1% NaOCl for 1 min, 75% ethanol for 30 s, and washed three times with sterile water. Pieces (1 cm3) were cut from the disinfested fruit, placed on potato dextrose agar (PDA), and incubated at 25°C for 1 week. Ten isolates with similar morphology were obtained and isolates SG66 and SG68 were selected for further characterization. Colonies maintained on PDA in the dark had an average radial growth rate of 10-12 mm/d at 25°C. Surface was white, velvety to felty mycelium. Reverse was white to pale wheat. Diffusible pigments were absent. On carnation leaf agar, sporodochia appeared as slimy dots, macroconidia were 3- to 5-septate, 20-35 × 3-5 µm, falcate, with a pronounced dorsiventral curvature, with blunt to papillate apical cell, and barely to distinctly notched basal cell. Microconidia and chlamydospores were not observed. These morphological characteristics were consistent with descriptions of Fusarium sp. DNA was extracted from isolates SG66 and SG68 using a CTAB method. Nucleotide sequences of the internal transcribed spacers (ITS) (White et al. 1990), calmodulin (CAM), RNA polymerase II second largest subunit (RPB2), and translation elongation factor 1-α gene (TEF1) (Xia et al. 2019) were amplified using generic primers, the products sequenced, and sequences deposited in GenBank (ITS: OP251362, OP251363; CAM: OP266024, OP266025; RPB2: OP266028, OP266029; TEF1: OP266026, OP266027). Isolates SG66 and SG68 clustered with Fusarium sulawesiense (85% bootstrap) (Maryani et al. 2019). The Fusarioid-ID database pairwise alignment of ITS (526 bp), CAM (534 bp), RPB2 (861 bp), and TEF1 (636 bp) sequences from isolate SG66 showed 99.6% (98.9% coverage), 100% (100% coverage), 100% (100% coverage) and 100% (98.4% coverage) similarity with the corresponding sequences (GQ505730, LS479422, LS479855 and GQ505641), respectively, of the reference strains of F. sulawesiense (InaCC F940 and NRRL 34059). To perform a pathogenicity test, 10 µl of conidial suspensions (1 × 106 conidia/ml) were injected into ten muskmelon fruit using a syringe, and ten control fruit were inoculated with 10 µl of sterile distilled water. The test was repeated three times. After 7 days at 25°C, the pulp of all inoculated muskmelons began to rot, and the lesion expanded from the inside to the fruit surface at the injection site and became covered with white mycelia. No symptoms developed on the control fruit. The fungus was successfully re-isolated from infected tissues and confirmed as F. sulawesiense by morphological and phylogenetic analyses. F. sulawesiense has previously been reported on yellow melon (Canary) in Brazil (Lima et al. 2021) and on a range of hosts, including Luffa aegyptiaca, in China (Wang et al. 2019). To our knowledge, this is the first report of muskmelon fruit rot caused by F. sulawesiense in China.

First Report of Muskmelon Fruit Rot Caused by Fusarium nanum in China.

Muskmelon (Cucumis melo L.) is one of the most widely cultivated and economically important fruit crops in the world. However, many pathogens can cause decay of muskmelon fruit, including Fusarium asiaticum, F. equiseti, F. incarnatum and F. lateritium (Hao et al. 2021; Wang et al. 2019). Fusarium spp. are the most important pathogens affecting muskmelon fruit yield and quality (Wang et al. 2011). In August 2020, fruit rot symptoms were observed on ripening muskmelons (cv. Tianbao) in several fields in Jiyang District, Jinan City of Shandong Province, China. The incidences of infected muskmelon ranged from 15% to 30% and caused an average 20% yield loss. Symptoms appeared as pale brown, water-soaked lesions that were irregular in shape, with the lesion sizes ranging from a small spot (1 to 2 cm) to decay of the entire fruit. The core and surface of infected fruit were colonized and covered with white mycelia. Two infected muskmelons were collected from two fields, 7 km apart. Tissues removed from inside the infected fruit were surface disinfected with 75% ethanol for 30 s, and cultured on potato dextrose agar (PDA) at 25°C in the dark for 5 days. Four purified cultures were obtained using the single spore method. On carnation leaf agar (CLA), macroconidia were 1 to 5 septate, falcate, with a pronounced dorsiventral curvature with blunt to papillate apical cell, and barely to distinctly notched basal cell, measuring 12 to 35 × 3.5 to 6 µm. Microconidia and chlamydospores were not observed. These morphological characteristics were consistent with the description of Fusarium sp. Because these isolates had similar morphology, two representative isolates (XP9 and XP10) were selected for multilocus phylogenetic analyses. DNA was extracted from the representative isolates using a CTAB method. Nucleotide sequences of the internal transcribed spacers (ITS) (White et al. 1990), calmodulin (CAM), RNA polymerase II second largest subunit (RPB2), translation elongation factor 1-α gene (TEF1) (Xia et al. 2019) were amplified using specific primers, sequenced, and deposited in GenBank (ITS: MW391507 and MW391508, CAM: MW392787 and MW392788, RPB2: MW392795 and MW392796, TEF1: MW392791 and MW392792). The Fusarium MLST database pairwise alignment of ITS (546 bp), CAM (628 bp), RPB2 (902 bp) and TEF1 (718 bp) sequences from isolate XP9 showed 99.63%, 99.33%, 100.00% and 99.71% similarity with the corresponding sequences (GQ505685, GQ505508, GQ505774 and GQ505596) of the reference strain of F. nanum (NRRL 22244), respectively. The overlap of ITS, CAM, RPB2 and TEF1 sequences from XP9 and NRRL 22244 were 100.00%, 95.06%, 97.45% and 94.99%, respectively. Alignments of a combined dataset of ITS, CAM, RPB2 and TEF1 were made using MAFFT v. 7, and phylogenetic analyses were conducted in MEGA v. 7.0 using the maximum likelihood method. The muskmelon isolates (XP9 and XP10) clustered together with the F. nanum reference strain CGMCC3.19498 and NRRL 22244 (100% bootstrap) (Wang et al., 2019). To perform a pathogenicity test, 10 µl of conidial suspensions (1 × 106 conidia/ml) were injected into each muskmelon fruit using a syringe, and the control fruit was inoculated with 10 µl of sterile distilled water. There were ten replicated fruits for each treatment. The test was repeated three times. After 7 days at 25°C, the interior of the inoculated muskmelons begun to rot, and the rot lesion expanded from the core towards the surface of the fruit, then white mycelia were produced on the surface. Ten isolations were re-isolated from the infected tissues and identified by morphological and phylogenetic analyses and confirmed to fulfill Koch's postulates. No symptoms were observed on the control muskmelons. To our knowledge, this is the first report of muskmelon fruit rot caused by F. nanum in China. Considering the economic value of the muskmelon crop, correct identification can help farmers select appropriate field management measures for control of this disease.

Phylogeny, Taxonomy and Morphological Characteristics of Apiospora (Amphisphaeriales, Apiosporaceae).

Apiospora is widely distributed throughout the world, and usually identified as endophytes, pathogens or saprobes. In this study, six strains were isolated from Bambusaceae sp., Prunus armeniaca, Salix babylonica and saprophytic leaves in Shandong Province, China. Three new species were identified based on a multi-locus gene phylogenetic analysis using a combined dataset of ITS, LSU, TEF1α and TUB2 in conjunction with morphological assessments. Apiospora armeniaca sp. nov., Apiospora babylonica sp. nov., and Apiospora jinanensis sp. nov. have been comprehensively described and illustrated, representing significant additions to the existing taxonomy.

Morphological and Phylogenetic Analyses Reveal Three New Species of Didymella (Didymellaceae, Pleosporales) from Jiangxi, China.

Didymella contains numerous plant pathogenic and saprobic species associated with a wide range of hosts. Over the course of our mycological surveys of plant pathogens from terrestrial plants in Jiangxi Province, China, eight strains isolated from diseased leaves of four host genera represented three new species of Didymella, D. bischofiae sp. nov., D. clerodendri sp. nov., and D. pittospori sp. nov. Phylogenetic analyses of combined ITS, LSU, RPB2, and TUB2 sequence data, using maximum-likelihood (ML) and Bayesian inference (BI), revealed their taxonomic placement within Didymella. Both morphological examinations and molecular phylogenetic analyses supported D. bischofiae, D. clerodendri, and D. pittospori as three new taxa within Didymella. Illustrations and descriptions of these three taxa were provided, along with comparisons with closely related taxa in the genus.

Phylogenomics, taxonomy and morphological characters of the Microdochiaceae (Xylariales, Sordariomycetes).

Species of the family Microdochiaceae (Xylariales, Sordariomycetes) have been reported from worldwide, and collected from different plant hosts. The proposed new genus and two new species, viz., Macroidriella gen. nov., M.bambusae sp. nov. and Microdochiumaustrale sp. nov., are based on multi-locus phylogenies from a combined dataset of ITS rDNA, LSU, RPB2 and TUB2 with morphological characteristics. Microdochiumsinense has been collected from diseased leaves of Phragmitesaustralis and this is the first report of the fungus on this host plant. Simultaneously, we annotated 10,372 to 11,863 genes, identified 4,909 single-copy orthologous genes, and conducted phylogenomic analysis based on genomic data. A gene family analysis was performed and it will expand the understanding of the evolutionary history and biodiversity of the Microdochiaceae. The detailed descriptions and illustrations of species are provided.

Morphological and Phylogenetic Analyses Reveal Three New Species of Pestalotiopsis (Sporocadaceae, Amphisphaeriales) from Hainan, China.

Species of Pestalotiopsis were mainly introduced as endophytes, plant pathogens or saprobes from various hosts. In this study, ten strains were isolated from Ficus macrocarpa, Phoebe zhennan and Spatholobus suberectus in China. Based on multilocus phylogenies from the internal transcribed spacer (ITS), the partial translation elongation factor 1-alpha gene (tef1α) and the partial beta-tubulin gene (tub2), in conjunction with morphological characteristics, we describe three new species, viz., Pestalotiopsis ficicola sp. nov., P. phoebes sp. nov. and P. spatholobi sp. nov.

Three New Species of Microdochium (Microdochiaceae, Xylariales) on Bambusaceae sp. and Saprophytic Leaves from Hainan and Yunnan, China.

Species of the genus Microdochium (Microdochiaceae, Xylariales) have been reported from the whole world and separated from multiple plant hosts. The primary aim of the present study is to describe and illustrate three new species isolated from the leaf spot of Bambusaceae sp. and saprophytic leaves in Hainan and Yunnan provinces, China. The proposed three species, viz., Microdochium bambusae, M. nannuoshanense and M. phyllosaprophyticum, are based on multi-locus phylogenies from a combined dataset of ITS rDNA, LSU, RPB2 and TUB2 in conjunction with morphological characteristics. Descriptions and illustrations of three new species in the genus are provided.

Taxonomy, Phylogeny, Divergence Time Estimation, and Biogeography of the Family Pseudoplagiostomataceae (Ascomycota, Diaporthales).

Species of Pseudoplagiostomataceae were mainly introduced as endophytes, plant pathogens, or saprobes from various hosts. Based on multi-locus phylogenies from the internal transcribed spacers (ITS), the large subunit of nuclear ribosomal RNA gene (LSU), partial DNA-directed RNA polymerase II subunit two gene (rpb2), the partial translation elongation factor 1-alpha gene (tef1α), and the partial beta-tubulin gene (tub2), in conjunction with morphological characteristics, we describe three new species, viz. Pseudoplagiostoma alsophilae sp. nov., P. bambusae sp. nov., and P. machili sp. nov. Molecular clock analyses on the divergence times of Pseudoplagiostomataceae indicated that the conjoint ancestor of Pseudoplagiostomataceae and Apoharknessiaceae occurred in the Cretaceous period. and had a mean stem age of 104.1 Mya (95% HPD of 86.0-129.0 Mya, 1.0 PP), and most species emerged in the Paleogene and Neogene period. Historical biogeography was reconstructed for Pseudoplagiostomataceae by the RASP software with a S-DEC model, and suggested that Asia, specifically Southeast Asia, was probably the ancestral area.

Morphological and phylogenetic analyses reveal two new species and a new record of Apiospora (Amphisphaeriales, Apiosporaceae) in China.

The genus Apiospora includes endophytes, pathogens and saprobes, with a wide host range and geographic distribution. In this paper, six Apiospora strains isolated from diseased and healthy tissues of bamboo leaves from Hainan and Shandong provinces in China were classified using a multi-locus phylogeny based on a combined dataset of ITS, LSU, tef1 and tub2, in conjunction with morphological characters, host association and ecological distribution. Two new species, Apiosporadongyingensis and A.hainanensis, and a new record of A.pseudosinensis in China, are described based on their distinct phylogenetic relationships and morphological analyses. Illustrations and descriptions of the three taxa are provided, along with comparisons with closely related taxa in the genus.

Multi-locus phylogenetic analyses reveal eight novel species of Distoseptispora from southern China.

IMPORTANCE: Distoseptispora as a single genus in Distoseptisporaceae was introduced by morphological and phylogenetic analyses. Members of this genus occur mainly as asexual morphs, forming effuse, hairy colonies on decaying wood, plant stems, bamboo culms, and fallen leaves and shafts in terrestrial and freshwater habitats. In the present study, saprobic hyphomycetes from plant debris were investigated, and eight new Distoseptispora species were introduced based on morphology and phylogenetic analyses of LSU, ITS, TEF1, and RPB2 sequence data. This study provides important data on the species diversity, ecological environment, and geographical area of Distoseptispora, greatly updates the classification of Distoseptispora, and improves our understanding of the taxonomy of Distoseptispora.